[PATCH 3.19 101/101] kvm: avoid page allocation failure in kvm_set_memory_region()

Greg Kroah-Hartman
2015-04-17T13:43:27Z

From: Igor Mammedov <imammedo@redhat.com>

commit 744961341d472db6272ed9b42319a90f5a2aa7c4 upstream.

KVM guest can fail to startup with following trace on host:

qemu-system-x86: page allocation failure: order:4, mode:0x40d0
Call Trace:
dump_stack+0x47/0x67
warn_alloc_failed+0xee/0x150
__alloc_pages_direct_compact+0x14a/0x150
__alloc_pages_nodemask+0x776/0xb80
alloc_kmem_pages+0x3a/0x110
kmalloc_order+0x13/0x50
kmemdup+0x1b/0x40
__kvm_set_memory_region+0x24a/0x9f0 [kvm]
kvm_set_ioapic+0x130/0x130 [kvm]
kvm_set_memory_region+0x21/0x40 [kvm]
kvm_vm_ioctl+0x43f/0x750 [kvm]

Failure happens when attempting to allocate pages for
'struct kvm_memslots', however it doesn't have to be
present in physically contiguous (kmalloc-ed) address
space, change allocation to kvm_kvzalloc() so that
it will be vmalloc-ed when its size is more then a page.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
virt/kvm/kvm_main.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -466,7 +466,7 @@ static struct kvm *kvm_create_vm(unsigne
BUILD_BUG_ON(KVM_MEM_SLOTS_NUM > SHRT_MAX);

r = -ENOMEM;
- kvm->memslots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
+ kvm->memslots = kvm_kvzalloc(sizeof(struct kvm_memslots));
if (!kvm->memslots)
goto out_err_no_srcu;

@@ -517,7 +517,7 @@ out_err_no_srcu:
out_err_no_disable:
for (i = 0; i < KVM_NR_BUSES; i++)
kfree(kvm->buses[i]);
- kfree(kvm->memslots);
+ kvfree(kvm->memslots);
kvm_arch_free_vm(kvm);
return ERR_PTR(r);
}
@@ -573,7 +573,7 @@ static void kvm_free_physmem(struct kvm
kvm_for_each_memslot(memslot, slots)
kvm_free_physmem_slot(kvm, memslot, NULL);

- kfree(kvm->memslots);
+ kvfree(kvm->memslots);
}

static void kvm_destroy_devices(struct kvm *kvm)
@@ -865,10 +865,10 @@ int __kvm_set_memory_region(struct kvm *
goto out_free;
}

- slots = kmemdup(kvm->memslots, sizeof(struct kvm_memslots),
- GFP_KERNEL);
+ slots = kvm_kvzalloc(sizeof(struct kvm_memslots));
if (!slots)
goto out_free;
+ memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));

if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
slot = id_to_memslot(slots, mem->slot);
@@ -911,7 +911,7 @@ int __kvm_set_memory_region(struct kvm *
kvm_arch_commit_memory_region(kvm, mem, &old, change);

kvm_free_physmem_slot(kvm, &old, &new);
- kfree(old_memslots);
+ kvfree(old_memslots);

/*
* IOMMU mapping: New slots need to be mapped. Old slots need to be
@@ -930,7 +930,7 @@ int __kvm_set_memory_region(struct kvm *
return 0;

out_slots:
- kfree(slots);
+ kvfree(slots);
out_free:
kvm_free_physmem_slot(kvm, &new, &old);